package com.asl.mp.util;

import org.springframework.http.HttpHeaders;
import org.springframework.http.server.reactive.ServerHttpRequest;

import javax.servlet.http.HttpServletRequest;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Optional;

/**
 * Created by @author XuYangW on 2019/7/15 0015.
 **/
public class NetworkUtil {
    private static final String[] IP_HEADER_CANDIDATES = {
            "X-Forwarded-For",
            "Proxy-Client-IP",
            "WL-Proxy-Client-IP",
            "HTTP_X_FORWARDED_FOR",
            "HTTP_X_FORWARDED",
            "HTTP_X_CLUSTER_CLIENT_IP",
            "HTTP_CLIENT_IP",
            "HTTP_FORWARDED_FOR",
            "HTTP_FORWARDED",
            "HTTP_VIA",
            "REMOTE_ADDR"
    };

    public static String getClientIP(HttpServletRequest request) {
        for (String header : IP_HEADER_CANDIDATES) {
            String ip = request.getHeader(header);
            if (ip != null && ip.length() != 0 && !"unknown".equalsIgnoreCase(ip)) {
                return ip;
            }
        }
        return request.getRemoteAddr();
    }

        private static final String IP_UNKNOWN = "unknown";
        private static final String IP_LOCAL = "127.0.0.1";
        private static final String IPV6_LOCAL = "0:0:0:0:0:0:0:1";
        private static final int IP_LEN = 15;
        /**
         * 获取用户真实IP地址，不直接使用request.getRemoteAddr();的原因是有可能用户使用了代理软件方式避免真实IP地址,
         *
         * 可是，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值，究竟哪个才是真正的用户端的真实IP呢？
         * 答案是取X-Forwarded-For中第一个非unknown的有效IP字符串。
         *
         * 如：X-Forwarded-For：192.168.1.110, 192.168.1.120, 192.168.1.130,
         * 192.168.1.100
         *
         * 用户真实IP为： 192.168.1.110
         *
         * @param request
         * @return
         */
        public static String getIpAddress(ServerHttpRequest request) {
            HttpHeaders headers = request.getHeaders();
            String ipAddress = headers.getFirst("x-forwarded-for");
            if (ipAddress == null || ipAddress.length() == 0 || IP_UNKNOWN.equalsIgnoreCase(ipAddress)) {
                ipAddress = headers.getFirst("Proxy-Client-IP");
            }
            if (ipAddress == null || ipAddress.length() == 0 || IP_UNKNOWN.equalsIgnoreCase(ipAddress)) {
                ipAddress = headers.getFirst("WL-Proxy-Client-IP");
            }
            if (ipAddress == null || ipAddress.length() == 0 || IP_UNKNOWN.equalsIgnoreCase(ipAddress)) {
                ipAddress = Optional.ofNullable(request.getRemoteAddress())
                        .map(address -> address.getAddress().getHostAddress())
                        .orElse("");
                if (IP_LOCAL.equals(ipAddress)|| IPV6_LOCAL.equals(ipAddress)) {
                    // 根据网卡取本机配置的IP
                    try {
                        InetAddress inet = InetAddress.getLocalHost();
                        ipAddress = inet.getHostAddress();
                    } catch (UnknownHostException e) {
                        // ignore
                    }
                }
            }

            // 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割
            if (ipAddress != null && ipAddress.length() > IP_LEN) {
                int index = ipAddress.indexOf(",");
                if (index > 0) {
                    ipAddress = ipAddress.substring(0, index);
                }
            }
            return ipAddress;
        }

        /**
         * 获取客户端端口
         * @param request
         * @return
         */
        public static Integer getPort(ServerHttpRequest request){
            return request.getRemoteAddress().getPort();
        }

    }
